A Wireless Fidelity (Wireless Fidelity, Wifi) system uses an unlicensed spectrum (unlicensed spectrum), and a Long Term Evolution (Long Term Evolution, LTE) system uses licensed 800 M, second-generation (2nd Generation, 2G), and 3.5-generation (3.5 Generation, 3.5G) spectrums.
Considering that licensed spectrum resources used in LTE are limited, an existing technology is as follows: When a Wi-Fi system does not effectively use its spectrum, the LTE system perceives usage of the spectrum of the Wi-Fi system and uses the spectrum. This technology is referred to as an unlicensed LTE (unlicensed LTE, U-LTE) technology.
When an LTE base station fails to effectively perceive a surrounding Wi-Fi AP, a hidden terminal problem (hidden terminal problem, HTP) may occur. For details, refer to FIG. 1.
In FIG. 1, because a signal loss during penetration is relatively large, an outdoor LTE base station fails to detect a signal transmitted by an indoor Wi-Fi AP. The LTE base station communicates with user equipment (User Equipment, UE). However, UE2 is close to the Wi-Fi AP. Consequently, a downlink signal transmitted by the Wi-Fi AP causes interference to communication between the LTE base station and the UE2, affecting communication between the LTE base station and the UE2.
In conclusion, when a network device fails to effectively perceive another network device, but uses a communication spectrum of the another network device to communicate with a terminal, communication between the network device and the terminal may be interfered with by the another network device.